package org.apache.lucene.store;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.*;

import org.apache.lucene.store.DataInput;

/**
 * A {@link DataInput} wrapping a plain {@link InputStream}.
 */
public class InputStreamDataInput extends DataInput implements Closeable {
    private final InputStream is;

    public InputStreamDataInput(InputStream is) {
        this.is = is;
    }

    @Override
    public byte readByte() throws IOException {
        int v = is.read();
        if (v == -1)
            throw new EOFException();
        return (byte) v;
    }

    @Override
    public void readBytes(byte[] b, int offset, int len) throws IOException {
        while (len > 0) {
            final int cnt = is.read(b, offset, len);
            if (cnt < 0) {
                // Partially read the input, but no more data available in the stream.
                throw new EOFException();
            }
            len -= cnt;
            offset += cnt;
        }
    }

    // @Override -- not until Java 1.6
    public void close() throws IOException {
        is.close();
    }
}
